Geometrical error correction based on sensitivity equations for accurate specular surface measurement with deflectometry

Li, Mengyang; Su, Chunzhou; Cao, Tingfen; Zhang, Jinli

doi:10.1080/09500340.2022.2067359

Cited by 2 publications

(1 citation statement)

References 16 publications

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“…The implementation process of the interface capture class method is generally complicated, and needs to be realized by means of special interface marking technology. So far people have developed a variety of interface capture methods [13][14] .…”

Section: Treatment Methods Of Free Surface Flowmentioning

confidence: 99%

Hydrodynamic Numerical Calculation Method of Small-scale Objects in Ocean Engineering Based on Immersion Boundary Method

2022

FOE

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Isolated piles, jacket platforms, submarine pipelines, etc. are ubiquitous structures in marine engineering. When the ratio of the lateral dimension D to the wavelength L of the part surrounded by waves is less than 0.2, it is generally called a small-scale structure. Current and waves are the two most important external loads in ocean engineering. The interaction between current and waves and small-scale structures in ocean engineering has always been the focus of research, and it is also one of the main problems that have not been well resolved in ocean engineering. In this paper, under the premise of considering the viscosity, turbulence and free surface flow of the fluid, the hydrodynamic problems related to small-scale objects in marine engineering are selected as the research content, and the numerical calculation model combining the immersion boundary method and the fluid volume method is selected for numerical calculation. The numerical expressions, solution steps and method verifications of the immersion boundary method and the fluid volume method are given respectively. A numerical calculation method by directly solving the external force source term in the immersion boundary method is proposed. The advantages, disadvantages and calculation steps of two different processing methods of applied force source terms in the immersion boundary method, continuous force method and discrete force method, are given. Instead of solving the force source term by means of interpolation and extrapolation, this paper adopts the discrete force method and the immersion boundary method for numerical calculation. Bounds method for numerical calculation. The realization process of establishing the numerical model of the immersion boundary method is given in detail. The finite difference method is used to discretize the governing equations and the semi-implicit two-step projection method is used to solve the NS equation. Finally, the numerical model of the immersion boundary method is given. Numerical realization process. The numerical model established in this paper is verified by the classical examples of numerical calculation of flow around a fixed cylinder and a flow around a rotating cylinder under laminar flow conditions, and the numerical calculation results are compared with the experimental and numerical results of others. The established numerical calculation model is correct and feasible. Experiments show that this model can well generate first-order Stokes linear waves. When a=0.25, according to the method proposed Frontiers in Ocean Engineering 2 in this paper, the lift can be reduced to 75%-80%; when a=0.5, the lift can be reduced to 60%; when a=0.75, the lift amplitude can be suppressed to 50% or less.

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Section: Treatment Methods Of Free Surface Flowmentioning

confidence: 99%

Hydrodynamic Numerical Calculation Method of Small-scale Objects in Ocean Engineering Based on Immersion Boundary Method

2022

FOE

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Ray tracing modeling and errors analysis for phase measuring deflectometry based on preset surface types

Wang,

Ma,

Yang

et al. 2024

Optical Metrology and Inspection for Industrial Applications XI

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In the current field of phase measuring deflectometry (PMD) techniques, the primary factor affecting the low-order shape errors of the measured specular surface originates from the uncertainty in geometric calibration. To address this issue, this paper presents a full simulation pipeline of PMD using the ray tracing technology within the Python framework. It integrates phase analysis and gradient-surface reconstruction algorithms based on preset surface types to analyze the error impact on the final retrieved profile, with the help of Zernike coefficients characterization. To further analyze the potential error influences of the PMD system in actual physical scenarios, a comprehensive ray tracing modeling simulation was conducted, considering system noises, nonlinear effects of the imaging subsystem, geometric calibration errors and the impact of displayer surface deformation. This simulation starts from forward ray tracing to construct the model of fringe signal propagation and combined it with reverse ray tracing to solve for the surface shape of the measured specular surface. It further clarifies that under the hybrid influence of comprehensive error sources, the primary contributing factors to the surface shape residuals of the measured mirror are low-order shape errors and certain high-order shape errors such as astigmatism and coma aberrations.

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Geometrical error correction based on sensitivity equations for accurate specular surface measurement with deflectometry

Cited by 2 publications

References 16 publications

Hydrodynamic Numerical Calculation Method of Small-scale Objects in Ocean Engineering Based on Immersion Boundary Method

Hydrodynamic Numerical Calculation Method of Small-scale Objects in Ocean Engineering Based on Immersion Boundary Method

Ray tracing modeling and errors analysis for phase measuring deflectometry based on preset surface types

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